Commercial alternating current (AC) is often used as a primary power source to power communication and data processing equipment which utilize stored program controls and solid-state integrated circuit technology. These circuits are generally very sensitive to any variations of the input power signal from its desired standard waveform. Commercial AC power waveforms are subject to many variations from the standard waveform due to the demands of other users on the power line and other extraneous factors. Undesirable power signal variations causing problems include overvoltage and under-voltage conditions, signal outages, and transient signals such as voltage spikes. These power signal variations may alter the stored data or switch signals and in extreme cases may damage the solid-state circuitry.